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Table 1 Summary of parameters, formulae and their description using data extracted from chlorophyll a fluorescence (OJIP) transient.

From: Antagonistic actions of boron against inhibitory effects of aluminum toxicity on growth, CO2 assimilation, ribulose-1,5-bisphosphate carboxylase/oxygenase, and photosynthetic electron transport probed by the JIP-test, of Citrus grandisseedlings

Fluorescence parameters Description
Extracted parameters  
Ft Fluorescence intensity at time t after onset of actinic illumination
F50 μsor F20 μs Minimum reliable recorded fluorescence at 50 μs with the PEA- or 20 μs with Handy-PEA-fluorimeter
F100 μs and F300 μs Fluorescence intensity at 100 and 300 μs, respectively
FJ and FI Fluorescence intensity at the J-step (2 ms) and the I-step (30 ms), respectively
FP (= Fm) Maximum recorded (= maximum possible) fluorescence at P-step
Area Total complementary area between fluorescence induction curve and F = Fm
Derived parameters  
Selected OJIP parameters  
Fo F50 μsor Fo F20 μs Minimum fluorescence, when all PSII RCs are open
Fm = FP Maximum fluorescence, when all PSII RCs are closed
VJ = (F2 ms - Fo)/(Fm - Fo) Relative variable fluorescence at the J-step (2 ms)
VI = (F30 ms - Fo)/(Fm - Fo) Relative variable fluorescence at the I-step (30 ms)
Mo = 4 (F300 μs - Fo)/(Fm - Fo) Approximated initial slope (in ms-1) of the fluorescence transient V = f(t)
VK = (F300 μs - Fo)/(Fm - Fo) Relative variable fluorescence at 300 μs
Sm = ECo/RC = Area/(Fm - Fo) Normalized total complementary area above the OJIP (reflecting multiple-turnover QA reduction events) or total electron carriers per RC
Fraction of OEC = [1 - (VK/VJ)]treated sample/[1 - (VK/VJ)]control The fraction of oxygen evolving centers (OEC) in comparison with control
Yields or flux ratios  
φPo = TRo/ABS = 1 - Fo/Fm = Fv/Fm Maximum quantum yield of primary photochemistry at t = 0
ψEo = ETo/TRo = 1 - VJ Probability (at time 0) that a trapped exciton moves an electron into the electron transport chain beyond QA-
φDo = DIo/ABS = 1 - φPo = Fo/Fm Quantum yield at t = 0 for energy dissipation
δRo = REo/ETo = (1 - VI)/(1 - VJ) Efficiency with which an electron can move from the reduced intersystem electron acceptors to the PSI end electron acceptors
φRo = REo/ABS = φPo × ψEo × δRo Quantum yield for the reduction of end acceptors of PSI per photon absorbed
Specific fluxes or activities expressed per reaction center (RC)
ABS/RC = Mo × (1/VJ) × (1/φPo) Absorption flux per RC
TRo/RC = Mo/VJ Trapped energy flux per RC at t = 0
ETo/RC = (Mo/VJ) × ψEo = (Mo/VJ) × (1 - VJ) Electron transport flux per RC at t = 0
DIo/RC = ABS/RC - TRo/RC Dissipated energy flux per RC at t = 0
REo/RC = (REo/ETo) × (ETo/RC) Reduction of end acceptors at PSI electron acceptor side per RC at t = 0
Phenomenological fluxes or activities expressed per excited cross section (CS)
DIo/CSo = ABS/CSo - TRo/CSo Dissipated energy flux per CS at t = 0
Performance index  
PItot,abs = (RC/ABS) × (φPo/(1 - φPo)) × (ψEo/(1 - ψEo)) × (δRo/(1 - δRo)) Total performance index, measuring the performance up to the PSI end electron acceptors